Comparison of Auto Y-Tool Versus Conventional Y-Tool for Improving Successful ESP Wellbore Access in H2S Oil Producer Wells

The use of Y-tool assemblies permits production logging and stimulation work in Electric Submersible Pump (ESP) oil well completions. Auto Y-tools use a valve design which preclude the need for a blanking plug used in conventional Y-tool completions and hence provides an alternative to the use of standard Y-tool assemblies in oil well completions. This paper; therefore, compares the use of an auto Y-tool as an enhanced alternative to conventional Y-tool completions for successful wellbore access below an ESP. To properly relate the operational requirements of conventional Y-tool during logging or stimulation activities, an Auto Y-tool design was identified and assessed based on its ability to automatically seal and unset above the bypass tubing depending on when ESP is in operation. An assessment of the compatibility of the metallurgy of the auto Y-tool components in an environment of high H2S partial pressure for the expected completion life was performed. Furthermore, an auto Y-tool installation would provide experience on its performance of the valve's benefit and its ability to seal and open as a means of enhancing natural flow production rate when the ESP is off. The auto Y-tool assessment proved better, easier and more efficient to use in ESP well completion to the conventional Y-Tool system. The auto-Y-tool provides faster access to the wellbore below the ESP string than the conventional system for a typical well intervention. There is no need for additional wireline or slickline activities following the initial rig installation. This, in turn, reduces the amount of man power required during well intervention for an ESP well completed with auto-Y-tool. It further reduces the amount of time used in such intervention, which has direct impact on the operational cost and production costs per barrel. The absence of blanking plug in the auto-Y-Tool assembly reduces pressure loss caused by friction due to flow through the ESP stages, thereby increasing the production rate for a natural flowing well when the ESP in not in operation. This paper includes example calculations for natural flow in different flow paths in ESP completions This paper offers operators a review of potential operational benefits of an auto Y-tool option to conventional Y-tool systems in ESP completion wellbore intervention.